Natures plus vitamin d3 1000 iu softgels are made with the highest quality vitamin d3 cholecalciferol and conform to the strictest standards for purity including californias proposition 65 citing the proven safety record of high potency vitamin d3 in clinical trials and noting the significant health benefits obtained nutrition scientists around the world have called for significantly raising the tolerable upper level and recommend a greater awareness of the need for such levels produ